A battery module including a battery cell assembly having at least one battery cell, a module case accommodating the battery cell assembly and including a first cover plate covering a first side of the battery cell assembly and a second cover plate covering a second side of the battery cell assembly, the second side being different from the first side, and at least one bolting member integrally fastened through the first cover plate and the second cover plate of the module case, wherein each bolting member includes a first portion fastened to the first cover plate and a second portion fastened to the second cover plate, the first and second portions of each bolting member have different diameters.